In recent years, gas turbines have increased in efficiency and size, and along with this, the intake of air from outside has increased. Due to the increase in the intake of the air, noise occurring in the air inlet of the gas turbine is a major problem. To reduce this noise, a silencer is attached to the air inlet of the gas turbine; however, the silencer is increased in size as the gas turbine is increased in size, and there is a demand for improvements in the durability of the silencer.
The structure of such a silencer may be configured by aligning a plurality of silencer panels so that plate surfaces thereof are parallel in the airflow direction. In order to reduce the noise resulting from the increased size of the gas turbine, there is a need to expand the length of the silencer panel in the airflow direction. At this time, it is necessary to divide the silencer panel in the airflow direction from the viewpoint of constraints on manufacturing or transport. A gap may occur in the divided silencer panel between an upstream silencer panel and a downstream silencer panel in a duct of the inlet of the gas turbine at the time of assembly. In particular, when the silencer panel is increased in size, the manufacturing precision for the lengths of the upstream silencer panel and the downstream silencer panel in the airflow direction is decreased, and there is a high possibility that the gap will be generated between both panels. When the gap is present between the upstream silencer panel and the downstream silencer panel, vortexes are generated in the airflow by air flowing from the upstream side into the gap, pressure loss occurs, and there is a possibility that secondary noise which is different to the noise accompanying the original airflow will be generated.
Examples of a gas turbine silencer for eliminating the above gap between the upstream silencer panel and the downstream silencer panel include the following. For example, Japanese Unexamined Patent Application Publication No. H07-224685A describes a silencer where an opening end of a gap adjusting cover with a U-shaped cross-section is fitted and fixed in one silencer panel, which is either of an upstream silencer panel and a downstream silencer panel, from a surface facing the other silencer panel. By adopting such a configuration, the gap between the one silencer panel where the gap adjusting cover is fixed and the other silencer panel is reduced to substantially zero due to thermal expansion of the material of the silencer panels caused by heat accompanying the flow of the airflow.
However, in the silencer described in Japanese Unexamined Patent Application Publication No. H07-224685A, variations are also generated in the thermal expansion of the silencer panel material due to variations in the heat generated by the flow of the airflow. For this reason, due to the variations in the thermal expansion of the silencer panel material, there is a possibility that the gap between the one silencer panel where the gap adjusting cover is fixed and the other silencer panel will not be reduced to substantially zero and that the gap will still remain. In such a case, vortexes are generated in the airflow by air flowing from the upstream side into the gap, pressure loss occurs, and secondary noise is generated. On the other hand, due to the thermal expansion of the silencer panel material, there is a possibility that the silencer panels will be deformed or damaged due to excessive contact between the one silencer panel where the gap adjusting cover is fixed and the other silencer panel. Furthermore, a step may be created in the plate surface of the silencer panel by the gap adjusting cover since the gap adjusting cover is fitted and fixed from the opening end with respect to the one silencer panel out of the upstream silencer panel and the downstream silencer panel. Due to this step, there is a possibility that disturbances will occur in the airflow and that secondary noise will be generated.